October 2010

World Premiere!
Master Builders
Lance Cochrane And Jim Nicholls
Review By Dick Olsher
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  They are out there. Serial tube amplifier builders whose wares seem to eventually find their way onto eBay. The really good ones develop a reputation, even a following. Their work represents the best of the DIY spirit and rests on a distillation of decades of tube circuitry wisdom. They have figured out what works and what doesn't by experimenting with dozens, and even hundreds of designs, and are able to separate the wheat from the chaff. This is your chance to purchase brand new, hand-made, tube amps that sound amazingly good at ridiculous prices. On the plus side, some of these designs are sonically superior to coveted 50s and 60s vintage gear that fetch kilo bucks on eBay and usually need a thorough restoration. On the "down side," you may often end up purchasing a one of a kind creation, and even in cases where the same design is being replicated, there is no guarantee that parts selection will be identical from unit to unit. Power transformers and output trannies may be recycled, as you will see, from some unusual sources. It would be appropriate to think of a master builder creation as a work of art – a unique object of sonic artistry – rather than a mass-produced commodity.

The Builders
It is time to shine the spot light on two individuals: Lance Cochrane -- the teacher -- and Jim Nicholls, one of his students. I connected with both of them on eBay and ended up purchasing a couple of their amps: Cochrane's Cherry Bomb and Nicholls' Midnight 807. Yes, I was curious, but beyond that I thought it would be fun to share my listening impressions with the DIY community and possibly even audiophiles at large. And I'm sure glad I took the plunge. These guys really know what they're doing. Before I tell you what I think of their work, I'd like to get up close and personal, and mostly in their own words (transcribed from email communications), get to know what makes them tick. I recognize that that in particular what Lance has to say, emotions and all, resonates with me as I'm sure it will with you.

Lance says that "Jim is only one of my students. It's easy to teach those that want to know. Impossible to teach those that only have the dream but not the drive. What I did years ago was take a stroke of luck and use it. I ran into a wonderful man, Tom Whalen and his Wife Vera at a garage sale. I actually was at one garage sale asking about old tube units and the fellow there told me that Tom had a sale on those type items the week before. I should go knock on his door. So I did. Tom was in his late 80's then. He had cataracts and despaired that when he passed away his kids would have to clean out all the leftovers from his old TV shop that cluttered his basement. I bought all I could afford and thought no more about it. About a year later I got a phone call from Tom. He wanted to know why I hadn't been back to pick up the rest of the contents of his basement. I hadn't known he seriously just wanted to give it all away but he did so I obliged."

"In the massive haul was roughly 300 pounds of old SAM'S Photofacts. Most of those were for old TV sets and completely useless. As I dug through the interminable mass of paper I kept finding schematics for tube amps. Classic tube amplifiers. Obscure tube amplifiers. Amplifiers with this variation on a circuit or that variation. I built them all. Well, most of them anyway. All the various permutations that I could find on page after page of wonders just given to me. I found as I built that a lot of fancy pants circuits, the stuff of legend really, was nothing worth bothering with. Bland mediocrity mostly. I also found that some simple circuits used by many makers because they were very cost effective to make and easy to render, were actually far better sounding than the sought after circuits used in the pricier models. A bit of tuning here, a bit of changing there, suddenly my units were better than rather gaudy amplifiers in no small measure."

"I've never tried to take any credit for advances in theory. I know nothing. I do know what sounds right though and that's what I try to get my students to realize. With the proper circuit I give them, they can easily handle over a direct set of specialized instructions so they can make superior amplifiers right at the start. They don't need to spend years building everything under the sun. Most of those projects are dead ends. I cut out all that for them. I spent too much time with my head to the grindstone finding what really was good and what was hype and hooey. The students can go right to it and build the good stuff straightaway. Schematics are only the starting point. They do get you 90% of the way there and that's a good start. To go from good to exceptional requires attention and listening. Bit more voltage here, little less resistance there. It's like cooking. You have to taste the mix in progress and adjust accordingly. With a bit of practice it's easy. HiFi is so much the land of smoke and mirrors. Broken dreams of yesterdays prose. Only so much of anything is real. I try to break through the illusions for my students so that they can see what is important and what is irrelevant. It's easy once they get a little practice and try the various silly things that the Audio World throws about."

"I've said for years that 95% of HiFi is hooey. It's most likely a higher percentage that that but let's neglect that for a moment. Inside the hooey wrapped in a delusion wrapped in a misguided marketers nightmare there really is a gleam of truth that once exposed, glows brightly in the minds of those that have the will to see it. I'm a limited man, a man of small dreams and meager imagination. Still, I've awakened some that would otherwise be silent. They dream new dreams and explore places that I haven't been. That's enough for me. Hopefully, they'll do the same. Thanks Tom and Vera. It's been a long time."

"When I started playing around with amplifiers I never gave a thought to creating units that would beat the best out there. Never considered the matter because I knew I couldn't. There were all these illustrious guys out there making beautiful units that made the magic, made the music come alive, made the writers drool. I was just a guy that was taking Chemistry in High School because I liked it. When I got to the electronics part of the Physics class I was hopeless. Not that I couldn't understand it on an intellectual plane, because I hated it. Just could not stand it. Good candidate for a master amp builder, right? Now I don't claim to ever have been a master builder. I just don't. There's a catch to that but in good conscience, I can't. When I started dabbling in audio it was about 1969 or so. I read all the luscious descriptions in the now defunct HiFi magazines about all the things I wanted but being a kid with no scratch I knew enough to dream quietly. Still, When a friend of mine took me over to a friend of a friend's house and the guy had KLH 9 Electrostatics and big Marantz amps and all the stuff that I dreamed about, well, I was still a kid but this guy who claimed to be a reviewer had all this stuff so, well, maybe anything was possible."

"I ended up gainfully employed a few years later with a pair of KLH 9's of my own. Marantz 8b too. Living the dream it seemed. Thing was, reality and dreams rarely coincide completely. I remember my mad friend Bob the bookie and his bulging eyes when he described how he met Bob Fulton and heard the Fulton Model J's and the music was dancing on the floor and on and on he babbled. Bob the bookie was like that. Bulging eyes and all was pretty common with him. Still, being a bookie he got those Fulton J's and then drove himself to further frenzy trying to find the perfect amplifier, turntable, preamplifier, what have you. He was crazy so he fit in perfectly with the audio community and better yet, thanks to the betting public he could afford to pursue his dreams directly into the jewelry stores that were the HiFi salons of the time."

"Being a humble hourly worker I followed a different course. I found old console amplifiers for $5 or so at garage sales and diddled a bit with them to get them working. Most were pretty good. Cheap and tacky looking sure, but good sounding. It was later on that I found out why. As I fiddled with the cheap console amps I learned to fix them. As word spread that I could fix things, all manner of hulks found their way over to my house. If you fix, you get them all. All the glittering jewelry store items from the HiFi salons that as a youth I knew I would only dream about, all those found their way to my doorstep. Well, not all but lots and lots did."

"There were a couple of revelations there. Firstly, a lot of the fancy pants components that I never could afford turned out to be nothing special. Some were really terrible. True, most were only mine until I had them fixed and returned but that was enough. Youthful dreams gone I knew then that the audio magazines I had read years before, indeed the ones on the shelves today, employed a legion of talented, creative writers. Creative they had to be because they were describing the units that I was listening to and repairing in such wondrous ways, verse to enchant while the units themselves had no such power. I learned about the delusion I had of the absolute superiority of the designers I held on high. I also learned of the enthralling nature of good, imaginative writing. The type writing I had slept through in English class had led me astray in my foolish quest. So there I was, deluded no longer, stripped of illusions that these super humans had attained some sort of otherworldly audio wonder, but still left wondering about the reality I had been left with."

"The simple and cheap console amps were better than my Marantz tube amplifier. Better than the ocean of boring McIntosh and truly regrettable Harmon Kardon tube units. Perhaps there was something there. There was. Most used a circuit rather similar to that in the Quad II units that I had grown fond of. Perhaps with some tinkering and some listening, perhaps. After seemingly forever, yes, there it was, better than anything I could buy. A finished and easy to reproduce circuit that actually beat the ultra expensive efforts of the commercial designers again and again."

"So if that's the case, and it is, why do I say that I'm no great designer, no idol to be worshiped, no icon shining in the distance personifying the best that can be? Simple, I'm not. I'm just a guy that likes to fiddle with things. Here's what I don't understand. When I get some highly lauded masterpiece, some Svengali of HiFi has created a marvel to behold that is lauded by the pundits, and when I get it over here to play with as sometimes happens even now in my dotage, usually the unit is smart looking but dumb sounding. It's not that my units are great, they're not, not at all. They just get it right and the others get it wrong. I don't understand how they sell that stuff. Sell it and get glowing reviews.

"I guess I'm world weary that way. It always reminds me of math class when there would be a problem with an obvious answer. Not something with a long funky formula that you had to stand on its head and do gyrations to get the result. Not like that. Where you could just look at it and there was the answer right in front of you like a beacon. A lot of guys couldn't see that beacon if you had pointed it right into their eyes. It's the same with audio. If it's right, it's obvious. If people leave the room when you have the stereo on it's outright bad. If they talk over it, it's boring. If they stop doing what they were doing and listen, it's right. It really is that simple. And still I see guys with glorified oil filled room heaters on Audiogon asking $25,000 a pair. The simple things are the hardest to grasp. That's life."

Jim has a true passion for tube circuits and vintage electronics. Lance, he says, "was kind enough to take me under his wing and teach me so much about the tube world, he has been building since 1970, did just about every circuit out there. …I have been into electronics and music since I can remember, always had lousy stereo equipment as a kid, my first "real" stereo system was one of those Realistic all in one jobs, I loved it, real stereo.. my own tape deck, (which never worked right).. paired that up with an old Akai tape deck and was in heaven.. Then came the guitar, I picked it up  at about 14 and couldn't put it down, got pretty darn good too, played in bands from 15 to the better part of my late 20's. I was the go to fix it guy, always repairing everyone's guitars, amps, and PA systems and enjoyed it."

"We got some decent mic's and a 8-track reel-to-reel and recorded often. I discovered the mighty Hammond organ and Leslie speaker, which really got me into tubes. I finally was able to find a nice B3 organ and Leslie speaker, the sound after I rebuilt the organ and amp floored me, I couldn't believe how much power and deep bass that 6550 amp could produce, it was awesome,. One day I decided my HK solid state receiver just did not cut it and went hunting for a nice amplifier, was shocked at some of the prices and just couldn't justify spending thousands, didn't have the means either. Then I stumbled upon one of Lance's auctions and that was it..must have asked that man over a million questions and still do to this day.. My philosophy is, there is no reason to spend a fortune on a good sounding tube amp.. I build them solid with quality parts and vintage transformers, not a fan of tweaking bias or balance pots either so all of my units are cathode biased with an auto balance driver circuit. Anyone can use one of my units and not have to know a lot about electronics, plug-and-play. I back my units up too, if ever an issue just send it over and I'll take care of it. This is still a fun hobby to me and I need to be sure it stays like that. I still do a 40 hour (sometimes more) work week. I currently work in center city Philadelphia (go Phillies, go Flyers!!) with three phase 480/277v electrical systems and industrial HVAC controls, motors and lighting systems.

The Amplifiers
Circuitry wise, Lance Cochrane designs typically feature a grounded-cathode input gain stage followed by a floating paraphase phase splitter. The input stage may even be dispensed with when the drive voltage requirement is modest, as in the case of the Cherry Bomb where the output tetrodes are operated at a low plate voltage of only 250 Vdc. The floating paraphase was quite popular in the late 1940s, though its popularity waned in the early 50s. And for some mysterious reason it gained a poor reputation as the stereo age dawned and it was quietly relegated to the dust bin of history. In fact, mainstream designers are apologetic nowadays about using it instead of the popular long-tailed pair or cathodyne. Take for example the Esoteric A-100, an $18,000 high-end cost-no-object design. I was told not to laugh out loud at the sight of a floating paraphase inverter, but they decided to use it because it was found to sound better than the alternatives. I certainly applaud the use of ears as an arbiter of sound quality rather than blindly trusting measurements.

None other than Norman Crowhurst was an advocate of the floating paraphase in the mid 1950s which he dubbed the seesaw circuit. The circuit comprises two triode sections, with the upper one feeding a fraction of its signal to the grid of the lower triode at the midpoint of a voltage divider connected to both plates. This is also where a fraction of the lower triode's output is fed back to its own grid and bucks the upper tube "seesaw" fashion, push-pull if you will. Crowhurst liked this circuit mostly for its simplicity, the fact that there is no heater-cathode voltage issues, and for its self-balancing action. The positive and negative going outputs stay balanced within 1% or so even with serious gain drifting between the two triodes. No, it's not perfect balance but the resultant distortion is minor relative to more serious tube amp distortion mechanisms. The two resistors that make up the voltage divider network are often shown as being of equal value, which of course would not allow a net grid signal to develop. For optimum performance these resistors need to be slightly offset in value, on the order of 5 to 15% depending on the gain of the phase inverter tube stage.

Both amps use a traditional output stage pentode connection, holding the screen at a fixed voltage slightly lower than the plate B+. The push-pull output stage is cathode biased, aka self-bias, to provide long-term stability and immunity from tube drift. Only a small amount of global feedback is used. The Midnight 807 uses a 6SN7 triode section for the input stage, and a 12AU7 dual triode for the phase inverter. Two pairs of 807 tetrodes operating push-pull comprise the output stage. The power supply is quite beefy and features a pair of paralleled 5Y3 rectifiers. According to Jim Nicholls, 5U4 rectifiers may also be used, though in that case he recommends premium 807/5933 due to increased voltage. The diminutive Cherry Bomb uses a pair of 12AT7s for phase splitting duties. The center tube (5965) is not used, but is available in case the amp were to be run at higher voltage requiring more drive voltage swing. It lights up ("glow for show" as Lance puts it) but is not in the circuit. The output stage can accommodate any 6L6 beam power tube type.

In both cases, the output transformers look suspiciously small. When I inquired, Jim informed me that the 807 amp output trannies are recycled from a Rowe jukebox, and that he uses them all the time when he can get them. He feels that bass is not an issue. They certainly sound terrific in the midrange and even the mid bass is robust, but I do miss deep bass, sub 40 Hz, extension. I don't think there enough primary inductance for that.

Sonic Impressions
The optimal load for both of these amps turned out to be the Basszilla Platinum Edition Mk.2 DIY speaker. A 96dB/W/m sensitive speaker only makes sense for the Cherry Bomb, nominally a 10 wpc power amp. Even so, the Bomb was most comfortable reproducing jazz, blues, and vocals and a bit reticent in linearly reproducing the dynamic breadth of symphonic music. The low plate voltage meant that I could safely roll in a quad of the original RCA 6L6 metal beam power tube, Navy NOS, dating most likely from the WWII era. Nice sweet mids with a cherry on top -- booyah! Its harmonic signature was recognizable with both solid-state and tube preamps: relaxed, slightly soft textures. The upper registers sounded a bit dark and tonality was skewed toward the midrange. Not surprisingly, it handled female voice gracefully. It was reasonably detailed and offered good soundstage transparency. It may not be the most accurate amp on the planet, but definitely fun to be around. What more could you ask for from a $500 investment.

Even a quick listen to the JWN 807 was sufficient to convince me that it merits comparison with far more expensive gear. Even with the stock tube complement, it boogied with uncommon verve unleashing an exceptional microdynamic palette. It threw a huge soundstage. Textures were smooth, rich with that big tone sound a 6SN7 is famous for. Colors were vivid, approaching the saturation of the real thing. Bass definition and control were surprisingly good; I would not have guessed that I was listening to pentode bass. And it was remarkably quiet.

Things got even better when I started experimenting with alternative 807 types. The best to date turned out to be a Sylvania JAN 5933 dating from 1952. The 5933 is a ruggedized 807 with a T12 bulb on a wide base. It isn't as sexy looking as the 807, but in this amp it provides more spacing between the tubes for better cooling. I also rolled in Mullard box anode CV4003 for the stock Sylvania 12AU7. Outfitted in this manner, image focus and soundstage transparency improved significantly. Partnered with the Mystère CA21 tube line stage, I can honestly say that I've never experienced more palpable image outlines. A reach-out-and-touch-someone realistic reproduction, perhaps the best money can buy. It became easy to peer deep into the soundstage. Although not a champ with respect to low-level detail, it was still possible to resolve transient decay and clearly identify vocal overdubs. The midrange was now to die for. Female voice timbre was stunningly realistic. Female vocals were projected with lovely harmonic bloom and fully intact emotional content. With the exception of the deep bass, the JWN 807 in my estimation exceeds the performance of the iconic Marantz 8B and Harman Kardon Citation II power amps. It projects a satisfying musical experience that should appeal to music lovers seeking to connect with the soul of the music. You would have to spend on the order of $10K retail to reach a similar level of musical satisfaction.

Contact Information
Jim Nicholls: website: jwnamplifiers.vpweb.com

Lance Cochrane: email: drat11@netzero.net